The correct option is A Sand and oil
Filtration is a method used for separating insoluble solids from the liquid, using a filter medium.
For example- When a mixture of sand and oil is filtered using a filter paper, the sand stays on the filter paper, while the oil passes through it.
But in the case of sugar and water mixtures as well as vinegar and water mixtures, components are well dissolved. They form solutions, where we do not have any undissolved components. Therefore, we cannot separate their components using filtration.
In case of milk and fat mixture, they form colloids. The fat components are dispersed in the water medium, and they do not settle down at bottom. Therefore, we cannot separate their components using filtration.